齿墩高度对齿墩内流消能工影响的试验研究

发布时间：2018-01-03 01:12

本文关键词：齿墩高度对齿墩内流消能工影响的试验研究　出处：《太原理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：齿墩内流消能工常用于有压管道和泄洪洞中构成一种新型内流消能工。本课题组前期已经对齿墩内流消能工在不同面积收缩比和不同齿墩数目两种情况的交叉方案进行了物理模型试验，得到了一些研究成果。本文是在前期研究的基础上，对齿墩内流消能工进行更深入的探索，在面积收缩比和齿墩数目一定的情况下，研究齿墩高度对内流消能工的影响。在本次试验中齿墩面积收缩比为0.5，齿墩数目为4，在不同流量下对5种不同齿墩高度（R1=50mm、R2=42.5mm、R3=37.5mm、R4=32.5mm、R5=25mm）的内流消能工进行了研究。通过物理模型试验试验和理论分析相结合的方法对齿墩内流消能工的压力特性、消能特性和空化特性进行了分析，得到了下面的一些结论：（1）不同齿墩高度的内流消能工其时均压强在整个试验段内的沿程分布规律基本一致，均在齿墩进口前时均压强迅速的减小并在齿墩段内降到最小值，随后时均压强逐渐的增大，在齿墩下游较远位置时均压强恢复平稳状态。其中方案R1在消能前后其时均压强的降幅最大，方案R3的时均压强降幅最小。（2）不同齿墩高度的内流消能工其流量系数随着雷诺数的增大有所增加，但当Re＞1.56×105其影响可忽略不计，各方案相比较R3的过流能力最大，比方案R1可增加约8%。（3）不同齿墩高度的内流消能工在雷诺数较小时对局部水头损失系数有一定的影响，雷诺数较大时其影响可忽略，其中流量较大时沿程水头损失约占总水头损失的10%左右。方案R1的局部水头损失最大，方案R3的最小。（4）不同齿墩高度的内流消能工其消能率均随着流量增加而增大，在试验范围内平均可达到60%左右。其中方案R1的消能率最好可达到63.84%；方案R2的消能率为57.41%；方案R3的消能率最差为51.18%；方案R4的消能率为60.71%；方案R5的消能率为59.80%。（5）不同齿墩高度的内流消能工其最小空化数都在齿墩段内0.2D的位置，当管道中的雷诺数达到3.11×105时最小空化数为负值。其中各方案比较方案R1的空化数最小，方案R5的空化数最大。空化数越小，越有可能发生空化现象。（6）不同齿墩高度的内流消能工其脉动压强沿程变化规律基本一致，均在齿墩段后1.6D的位置处脉动压强变化剧烈。在流量较大时各方案中R1的压强脉动最强，方案R5的压强脉动最弱。（7）不同齿墩高度的内流消能工综合分析，，方案R5（齿墩高度为25mm）最不易发生空化，同时其过流能力和消能率也较佳，应为首要选择。
[Abstract]:The tooth pier energy dissipator used in pressure piping and drainage in Hongdong to form a new type of energy dissipator. Ourprevious has the tooth pier energy dissipator of physical model test in different area contraction ratio and different cross schemes tooth block number two cases, got a some research results. This paper is on the basis of previous studies, energy dissipation for a more in-depth exploration of the tooth in the pier, the area contraction ratio and tooth block number under certain circumstances, research on tooth height of pier flow dissipator on the inside. In this experiment the tooth area contraction ratio of pier 0.5, the number of teeth of pier 4, different flow in 5 different kinds of tooth height of Pier (R1=50mm, R2=42.5mm, R3=37.5mm, R4=32.5mm, R5=25mm) dissipator was studied. The flow pressure characteristic by the combined method of physical model test and theoretical analysis of the test on energy dissipator tooth in the pier flow and energy dissipation The characteristics and cavitation characteristics are analyzed, and some conclusions are obtained.
(1) the different tooth height of pier energy dissipator time average pressure in the test section. The distribution law is basically consistent, both in dental average pressure drops rapidly when imports and down to the pier section in tooth minimum, average pressure gradually increases. Then, in the teeth of pier is lower off position of mean pressure recovery scheme of R1 in steady state. The energy before and after the time average pressure the largest decline, R3 mean pressure drop minimum.
(2) the flow coefficient of the internal flow energy dissipator with different tooth height is increased with the increase of Reynolds number, but when Re > 1.56 * 105, its influence is negligible. Compared with R3, the flow capacity of each scheme is the largest, which is increased by about 8%. compared with the scheme R1.
(3) the different tooth height of pier energy dissipator has certain influence on the coefficient of local head loss when the Reynolds number is small, the Reynolds number increases its influence can be ignored, which is about the larger flow of water head loss along the total head loss of 10%. The local head loss R1 scheme, R3 scheme the minimum.
(4) the different tooth height of pier energy dissipator and its dissipation rate is increased as the flow rate increases, the average in the test range can reach about 60%. The best scheme of R1 energy dissipation rate can reach 63.84%; R2 energy dissipation rate is 57.41%; R3 is the worst energy dissipation rate is 51.18%; scheme R4 the energy dissipation rate is 60.71%; energy dissipation scheme of R5 for 59.80%.
(5) the different tooth height of pier energy dissipator of the minimum cavitation number are 0.2D in the tooth position within the pier section, when the Reynolds number in the pipeline to reach 3.11 * 105 minimum cavitation number is negative. The cavitation number of each scheme comparison scheme of R1 minimum, the cavitation number scheme of R5. The maximum cavitation number the smaller, the more likely occurrence of cavitation phenomenon.
(6) the fluctuating pressure of the internal flow energy dissipator with different piers height is basically the same along the way. The fluctuating pressure changes fiercely at the position of 1.6D after the pier section. When the flow rate is large, the pressure pulsation of R1 is the strongest in each scheme, and the pressure pulsation of plan R5 is the weakest.
(7) the different tooth height of pier energy dissipator comprehensive analysis, scheme R5 (tooth pier height 25mm) the most easy occurrence of cavitation, and the flow capacity and energy dissipation is better, should be the first choice.

【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TV653

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